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Publication numberUS5909012 A
Publication typeGrant
Application numberUS 08/730,618
Publication dateJun 1, 1999
Filing dateOct 21, 1996
Priority dateOct 21, 1996
Fee statusLapsed
Publication number08730618, 730618, US 5909012 A, US 5909012A, US-A-5909012, US5909012 A, US5909012A
InventorsMichael George Todd, Charles Frederick Schweitzer, Robert Edward Belke, Jr., Tianmin Zheng
Original AssigneeFord Motor Company
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Method of making a three-dimensional part with buried conductors
US 5909012 A
Abstract
A gas assisted injection molded part includes internal cavities extending between two surfaces of the part. The cavities are plated for electrical conductivity after a surface cleaning and etching process. The part may be an automobile instrument panel wherein the internal cavities are plated to create a series of "bus" conductor lines. These lines carry power, ground and/or electrical signals over relatively large distances, allowing other components to attach at points along the structure eliminating the need for discrete wiring and wire harness interconnect assemblies.
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Claims(11)
What is claimed is:
1. An interconnect device formed of molded plastic material, said device having an arcuate cross-section, a longitudinal dimension and including:
a plurality of internal cavities having a high aspect ratio and extending between first and second surfaces across substantially all of said longitudinal dimension of said device;
said cavities plated with a conductive material to form internal conductors;
at least one surface conductor formed on a third surface of said device;
means connecting said surface conductor with at least one of said internal conductors to establish a path for carrying current through said at least one of said internal conductors and said surface conductor.
2. The device of claim 1 wherein one or more of said conductors connects a source of current with a load.
3. The device of claim 1, wherein the means connecting said surface conductor with said at least one of said internal conductors comprises a plated hole in said material.
4. The device of claim 1, wherein said cavities follow the arcuate cross-section of the device.
5. The device of claim 4, wherein each cavity terminates in an opening at each of said first and second surfaces.
6. The device of claim 5, wherein said device is a vehicle instrument panel.
7. An interconnect device formed of molded plastic material, said device having an arcuate cross-section and a longitudinal dimension and including:
a plurality of internal cavities having a relatively large depth to diameter ratio, extending between first and second surfaces across substantially all of said longitudinal dimension of said device;
said cavities plated with a conductive material to form internal conductors that follow the arcuate cross-section of the device;
at least one surface conductor formed on a third surface of said device;
means connecting said surface conductor with at least one of said internal conductors to establish a path for carrying current through said at least one of said internal conductors and said surface conductor.
8. The device of claim 7, wherein at least another one of said internal conductors is connected with a source of current and is also connected with a load.
9. The device of claim 7, wherein the means connecting said surface conductor with said at least one of said internal conductors comprises a plated hole in said material.
10. The device of claim 7, wherein each cavity terminates in an opening at each of said first and second surfaces.
11. The device of claim 7, wherein said device is a vehicle instrument panel.
Description
TECHNICAL FIELD

This invention relates to the manufacture of three-dimensional molded plastic parts used for supporting interconnected electrical components and, more particularly, to a manufacturing process that uses electroless metal deposition to plate internal cavities in plastic parts, such as those formed by gas assist injection molding, to form an electrically insulative base substrate containing internal or buried conductor for interconnecting such components.

BACKGROUND ART

Plating of electrical conductors on mechanically functional three-dimensional plastic parts is gaining increased acceptance in the mechanical and electrical design communities. These electrical/mechanical hybrid devices are generally known as "molded interconnect devices", or MIDs. There are a number of methods known for the manufacture of MIDs including electroplating, electroless plating, foil embossing, and circuit film in-molding. However, one of the limitation in each of these technologies is that they are not capable of plating more than a single electrical layer on each plastic surface. This is a severe limitation since most circuits designed today take advantage of multiple electrical conductor layers (for example, multi-layer FR-4 circuits).

Manufacturing methods such as gas assist injection molding, blow-molding and lost-core molding produce complex three-dimensional plastic or composite parts having internal cavities void of plastic material. These cavities generally serve the purposes of providing required structural support, reducing overall material usage in a part, and preventing poor molding features such as "sinks" or short shots.

SUMMARY OF THE INVENTION

In accordance with the present invention, the limitations of the prior art are overcome by taking advantage of the internal cavities in the aforementioned plastic molded components by plating the internal cavities to form current carrying conductors that may be suitably connected between a source and an output device. The internal cavities to be plated are subjected to a surface cleaning and etching process followed by electroless deposition of the metal conductor. The invention thus produces electrically conductive regions or traces inside a three-dimensional part that can be used as (1) electrical conductors for power, ground or signal transfer within the part, or (2) EMI shielding between one or more conductive circuit layers formed on the external surfaces of the molded part.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention may be had from the following detailed description which should be read in conjunction with the drawings in which:

FIG. 1 is a plan view of a part produced in accordance with the present invention;

FIG. 2 is a pictorial representation of the plating process used to plate conductive material in the cavities of the three-dimensional molded part;

FIG. 3 is an enlarged partial cross-sectional view of a portion of the part showing the plating on the inner wall of the cavities and the electrical connection between surface and buried conductors; and

FIG. 4 is a plan view of a second part produced in accordance with the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

Referring now to the drawings and initially to FIG. 1, a molded plastic substrate or part generally designated 10 which may, for example, represent a portion of an automobile instrument panel. The part 10 has a generally arcuate cross-section and a longitudinal dimension and includes a plurality of elongated, generally cylindrically shaped cavities 12-24 extending from one surface 26 to other surfaces 28 and 30 across substantially all of the longitudinal dimension. The cavities 12-24 have a high aspect ratio, that is, the cavities have a relatively large depth to diameter ratio. The part 10 with the internal cavities is produced by a suitable injection molding process, preferably gas assist injection molding. This process includes a partial injection of polymer melt in the mold cavity, followed by introducing compressed gas to create the hollow cavities 12-24.

In order to plate these internal cavities for electrical conductivity, it is first necessary to prepare the surface of the part to be plated. This preparation require a surface cleaning and etching process which is well known and need not be described in detail. These processes create microscopic irregularities on the plastic surface to increase plating adhesion.

The preparation step is followed by electroless deposition of the metal conductor in the manner shown in FIG. 2. Electroless plating baths are well known that deposit copper, nickel or gold. In order to effectively plate the internal cavities of these parts using an electroless metal plating system, it is desirable to ensure adequate flow rates of the plating solution through the internal cavities. This may be achieved by positioning the part 10, using a suitable support structure 32, within a plating tank 34 such that the openings of the cavities align with the flow of the plating solution from a circulation pump 36 through bellows 38 and 40. The plating solution adheres to the inner walls of the cavities as best shown in FIG. 3 at 42. Alternately, "plating lines" consisting of plastic or metal tubes through which plating solution flows may be connected to a circulation pump on one end, and the part cavities on the other, thereby pumping solution directly through the internal cavities of the molded part. This latter configuration may also be utilized to selectively plate only the internal cavities of the part (without plating the exterior), or to plate only selected internal cavities.

Holes may be designed into the mold or drilled to provide points for interconnection between exterior conductor (not shown) that may be placed on the exterior surface of the part, thereby creating integral plate through holes.

Depending upon the configuration of the molded part, the internal plated cavities may serve to function as electrical conductor lines for the carrying of electrical current or signals. Because the entire wall of the cavity is plated, as indicated in FIG. 3 at 42, relatively high current carrying capacity traces may be created using a small space, due to the large surface area of the cavities. The cavities generally follows the arcuate cross-section of the part and each cavity terminates in an opening at the surface of the part.

As shown in FIG. 4, a large flat cavity area 44 may be created within a molded part 46. This large area, when plated as at 48, may serve as an effective EMI (electromagnetic interference) shield. The plated area shields exterior surface carrying conductors 50 from the environment, or may shield one exterior surface carrying conductor from another exterior surface carrying conductor (not shown).

One of numerous applications of the present invention is an automobile instrument panel wherein the internal cavities may be plated to create a series of "bus" conductor lines. These lines would carry power, ground and/or electrical signals over relatively large distances, allowing other components to attach at points along the structure. This structure eliminates the need for discrete wiring and wire harness interconnect assemblies. This use is shown schematically in FIG. 1, where a battery 52 is electrically connected with a resistor or other load, generally indicated at 54, through the conductive material plated on the walls of the cavity 12. Conductors 56 and 58 are shown as formed on the surface of the part 10 and may connect other loads through drilled or molded holes 60 and 62 in the part 10. As best shown in FIG. 3, the holes 60 and 62 are plated as at 64 and may connect the surface conductors with a buried or internal conductor and thence to the battery 52.

While the best mode for carrying out the present invention has been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention as defined by the following claims.

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Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US6042425 *Apr 22, 1998Mar 28, 2000Mannesmann AktiengesellschaftConnection element for providing an electrical connection to electrical elements arranged in a group
US6343954 *Jun 14, 2000Feb 5, 2002Raytheon CompanyIntegral missile harness-fairing assembly
US6431638Nov 9, 2000Aug 13, 2002The Budd CompanyAutomobile lift gate
US6727436 *Mar 15, 2002Apr 27, 2004Memx, Inc.Interconnect bus crossover for MEMS
US7273401Mar 15, 2004Sep 25, 2007Molex IncorporatedGrouped element transmission channel link with pedestal aspects
US7699672May 17, 2007Apr 20, 2010Molex IncorporatedGrouped element transmission channel link with pedestal aspects
US7753744Mar 24, 2009Jul 13, 2010Molex IncorporatedGrouped element transmission channel link with pedestal aspects
US8006075May 21, 2009Aug 23, 2011Oracle America, Inc.Dynamically allocated store queue for a multithreaded processor
US8192657Nov 22, 2007Jun 5, 2012Nederlandse Organisatie Voor Toegepast-Natuurwetenschappelijk Onderzoek TnoProduct with internal cavities, and method, system and mould for manufacturing such a product
US8749991 *May 10, 2010Jun 10, 2014Toyota Motor Engineering & Manufacturing North America, Inc.Audio amplifier assembly having grounding bracket
US20110274287 *May 10, 2010Nov 10, 2011Toyota Motor Engineering & Manufacturing North America, Inc.Audio amplifier assembly having grounding bracket
EP1925419A1 *Nov 22, 2006May 28, 2008Nederlandse Organisatie voor Toegepast-Natuuurwetenschappelijk Onderzoek TNOProduct having a solid body and inside hollow rooms
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EP1937044A1 *Dec 22, 2006Jun 25, 2008Nederlandse Organisatie voor toegepast- natuurwetenschappelijk onderzoek TNOMethod for manufacturing a conductor
EP2131044A2 *May 27, 2009Dec 9, 2009Robert Bosch GmbHDevice for electric connection of several electropneumatic valves arranged as a valve unit
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WO2004084421A2 *Mar 15, 2004Sep 30, 2004Molex IncGrouped element transmission channel link with pedestal aspects
WO2008063063A1 *Nov 22, 2007May 29, 2008TnoProduct with internal cavities, and method, system and mould for manufacturing such a product
Classifications
U.S. Classification174/266, 361/823, 439/654
International ClassificationH05K1/00, H05K3/18, H05K3/40, H05K1/02, B29C45/00, B29C45/17
Cooperative ClassificationH05K1/0218, B29L2031/3493, B29C45/0053, H05K3/187, H05K1/0284, B29C45/1704, B29C2045/0079, H05K1/0272, H05K2201/09118, H05K2201/09163, H05K2201/09981, H05K3/403, H05K2201/09627
European ClassificationH05K3/18B3, H05K3/40C, H05K1/02F, H05K1/02C2B
Legal Events
DateCodeEventDescription
Oct 7, 2010ASAssignment
Owner name: VISTEON GLOBAL TECHNOLOGIES, INC., MICHIGAN
Free format text: RELEASE BY SECURED PARTY AGAINST SECURITY INTEREST IN PATENTS RECORDED AT REEL 022575 FRAME 0186;ASSIGNOR:WILMINGTON TRUST FSB, AS ADMINISTRATIVE AGENT;REEL/FRAME:025105/0201
Effective date: 20101001
Apr 21, 2009ASAssignment
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Free format text: ASSIGNMENT OF SECURITY INTEREST IN PATENTS;ASSIGNOR:JPMORGAN CHASE BANK, N.A., AS ADMINISTRATIVE AGENT;REEL/FRAME:022575/0186
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Feb 27, 2009ASAssignment
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Free format text: SECURITY INTEREST;ASSIGNOR:VISTEON GLOBAL TECHNOLOGIES, INC.;REEL/FRAME:022368/0001
Effective date: 20060814
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Free format text: SECURITY INTEREST;ASSIGNOR:VISTEON GLOBAL TECHNOLOGIES, INC.;REEL/FRAME:22368/1
Jul 24, 2007FPExpired due to failure to pay maintenance fee
Effective date: 20070601
Jun 1, 2007LAPSLapse for failure to pay maintenance fees
Dec 20, 2006REMIMaintenance fee reminder mailed
Oct 17, 2002FPAYFee payment
Year of fee payment: 4
Jun 20, 2000ASAssignment
Owner name: VISTEON GLOBAL TECHNOLOGIES, INC., MICHIGAN
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:FORD MOTOR COMPANY;REEL/FRAME:010968/0220
Effective date: 20000615
Owner name: VISTEON GLOBAL TECHNOLOGIES, INC. 1 PARKLANE BOULE
Jul 14, 1997ASAssignment
Owner name: FORD MOTOR COMPANY, MICHIGAN
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:TODD, MICHAEL GEORGE;SCHWEITZER, CHARLES FREDERICK;BELKE, ROBERT EDWARD, JR.;AND OTHERS;REEL/FRAME:008600/0154
Effective date: 19961016